The Puerto Rico Region and Monroe County, Florida will maintain a log of all blood donors enrolled by collection date documenting the time of collection, centrifugation and freezing; only centrifuged and frozen PPTs will be sent to the Charlotte NTL for NS1 Ag testing. Samples frozen when received at the Charlotte NTL will be tested. Samples that arrive thawed will be tested if the time unfrozen is 24 hours or less. When necessary, alternate PPTs (surplus samples used for NAT) will be used for dengue NS1 Ag testing; a log will be kept by the Charlotte NTL documenting the sample identification numbers of thawed samples, approximate time unfrozen and the samples that require an alternate PPT for dengue NS1 Ag testing.